The stock market gained ground on Wednesday, sending several major indexes to record highs. Investors remain upbeat about the potential for long-term economic growth, with increasing confidence that the Federal Reserve will step in to cut rates in an effort to keep the U.S. economy out of recession. Even in a shortened trading session in advance of the July 4 holiday, several stocks posted substantial gains. Symantec (NASDAQ:SYMC), NIO (NYSE:NIO), and Karyopharm Therapeutics (NASDAQ:KPTI) were among the top performers. Here's why they did so well.

Symantec gets buying interest

Shares of Symantec jumped nearly 14% after news surfaced that it might be an acquisition target. Reports late Tuesday suggested that Broadcom was discussing buying out Symantec, and analysts weighed in with their assessment that any potential deal could fetch somewhere between $26 and $28 per share for Symantec investors. That might sound like a big premium, but it's not that much higher than where the cybersecurity specialist's shares traded before its most recent earnings report. Yet with former CEO Greg Clark having stepped down unexpectedly, many see an acquisition as the best way to make the most of Symantec's business opportunities.

Blue sportscar with doors open vertically.

Image source: NIO.

NIO drives higher

NIO saw its stock climb 11% as the Chinese electric vehicle manufacturer rode on the coattails of its U.S. counterpart. Yesterday afternoon, Tesla reported its production and delivery figures for the second quarter, and the numbers reached record levels and indicated extremely strong demand for the company's vehicles. NIO is trying to capture some of the same trends in the Chinese auto market, and investors seem to think that what's good for Tesla should also work for NIO. Even with today's gains, though, NIO has struggled, and its stock is down 70% since March.

Karyopharm gets a thumbs-up

Finally, shares of Karyopharm Therapeutics soared 36%. The cancer-fighting-drug maker announced that its Xpovio treatment for patients with multiple myeloma has received approval from the U.S. Food and Drug Administration. Karyopharm did note that continued approval for the specific indication, which identifies only certain groups of multiple myeloma patients, might be contingent on verification of the clinical benefit from the drug in confirmatory trials. Investors had hoped that an FDA decision to extend the period for approving Xpovio back in March was a positive sign, and as it turns out, their patience got rewarded.